It could be as simple as "not greater than 26 years of age". Which is actually similar to the wording they use to describe the low end (19). No one seems to question that side of it.
Even established NRD/NTAG recruiters stumble on it. And it is a question that is asked by potential applicants savvy enough to google the PA themselves. I even discussed (phonecon) with the Pilot OCM and he stumbled!
But, like you said, I'll take it on the chin for my comprehension. I'm just glad the Nuke manuals weren't written that way...could be trouble!